Crankshaft position sensor

Crankshaft Position Sensor

The functional objective for the crankshaft position sensor is to determine the position and/or rotational speed (RPM) of the crank. Engine control unit use the information transmitted by the sensor to control parameters such as ignition timing and fuel injection timing. The sensor output can also be related to other sensor data including the cam position to derive the current combustion cycle, this is very important for the starting of a four stroke engine. The Crankshaft Position Sensor (CPK) is always located somewhere on the engine in close proximity to the crankshaft, usually near the harmonic balancer or in the engine block aligned with a toothed wheel connected to the crankshaft. The CPK provides the data that is used to compute the engine's revolutions per minute (RPM), which is essential for proper transmission gear selection in relationship to vehicle speed and load.

Failure Symptoms

• There are three primary engine malfunction symptoms that may be indicators of CPK malfunction. If the vehicle engine is experiencing cylinder misfires, the CPK may not be providing the computer with accurate information on piston position. If the vehicle hesitates during acceleration, the CPK may not be providing cylinder position data to the computer fast enough to fire the appropriate cylinder to accelerate the vehicle in response to driver input. The most serious indication of CPK malfunction is intermittent start, and eventually no start. When the sensor fails, the computer will register a malfunction code and illuminate the check engine light on the instrument panel. There may be an indication of sensor failure due to defective electrical connections such as high resistance, or an open condition in the circuit going to the sensor or returning to the vehicle engine control module.